The ship crash-lands in the Evil Forest and Garnet is missing. You have your first Active Time Event (ATE) here - "The Forest Keeper" - of Garnet and Vivi being lost in the forest.

Mosco the Moogle is by the ship to save if you wish. There's a phoenix down above the boxes. Grab it, then head through the log to the southeast.

In the first room you'll fight with your first real monsters - pretty easy. You should hit Level 3 while in this first room, and get at least a Fang card.

In the second room, you fight the Prison Cage plant with Steiner. Be sure to give her potions every once in a while during the fight - if she drops to 0 points, the game is over. It takes around 12 hits to drive off the cage, with it healing itself around 3 times.

Now Vivi is captured. At least Vivi helps by magic-blasting its cage with fire. It takes around 9 hits before this one dies, drenching you all with spores. You wake up back on the ship, where you are being healed.